Also why is enable-opal-multi-threads required for MPI_THREAD_FUNNELED? This
was asked before (e.g.
http://www.open-mpi.org/community/lists/devel/2010/05/7900.php) but I
couldn't find any answer. What does the option change? The README
states: "Enables
thread lock support in the OPAL and ORTE layers.", but that is not very
useful for a user. Also why is it not enabled by default?